Bacillus thuringiensis, is well-known for use as a microbial insect pathogen useful against leaf-chewing insects such as the alfalfa caterpillar, the cosmopolitan green beetle, the European corn borer and the Mediterranean flower moth. See, for example, U.S. Pat. No. 3,150,062. Although used for the toxic effects on general agricultural and forest leaf-chewing insect pests, Bacillus thuringiensis, has no substantial effect on sucking insects such as aphids and the like.
The search has continued for ways to increase the potency, toxicity, and/or persistance of insecticides, including Bacillus thuringiensis. Its use, at present, is limited to the control of early instars of the lepidoptera.
Many chemical insecticides, which are useful in controlling insects, do not control well the insect larvae belonging to the order of lepidoptera.
The search has continued for a more efficacious manner of utilizing Bacillus thuringiensis as a broader control insecticide. Bacillus thuringiensis has been suggested for use in admixture with various other insecticides, acarides or liquid carriers. See, for example, U.S. Pat. Nos. 3,946,107; 3,236,622; 3,911,110; 3,937,813; 3,944,664; and 4,000,258.
Another known insect growth regulator is 1-(4-chlorophenyl)-3(2,6-difluorobenzoyl)-urea available under the trademark "Dimilin". This compound, which is also referred to as N-4-chlorophenyl amino carbonyl-2,6-difluorobenzamide, is a chitin inhibitor effective against several economic pests, particularly foliar feeding lepidopterous insects.